Had a similar problem on my s14 sr. Check coil packs, plugs, check what your vacuum is, mine read around -21 which is where it needs to be. Could be a dying fuel pump. I tinkered with my car for almost a month checking and rechecking, buying a pump and tps...ended up being bad wiring at the IAC valve, so i cut and resoldered the wires, Bamm, ran like a champ.
Hope you get it fixed, i know first hand the shitty feeling
Good luck bro